At 10:24 AM 3/3/5, Edmund Storms wrote: >You forget Nick, that hydrogen will be mainly obtained from water. As a >result, each hydrogen atom that is produced is accompanied by the >necessary oxygen for its conversion back to water.
I think that was Nick's point too. Also of interest is the fact that even if the primary source of energy for the hydrogen is methane gas, and the carbon is sequestered, there is a lot more oxygen around than the web site indicates. Using 15 lb/in^2 air pressure, that's rho = 1.055x10^4 kg/m^2 of atmosphere above the earth's surface. Using 6378 km as earth's radius R, we have area A = 4 Pi R^2 = 5.11x10^14 m^2. Total mass of the atmosphere is M_atmos = Rho * A = 5.39x10^18 kg. Total mass of oxygen is roughly 1/5 that or about 1.078x10^18 kg. We can afford to lose about 1/3 of that before life gets tough, or about 3.59x10^17 kg. Using H2 + 0.5 O2 -> H2O + 228 kJ/mol, we get 228 kJ per 16 g of oxygen burned, or 1.425x10^7 J/kg of O2 burned, or 1.35x10^4 Btu/kg. Since world energy consumption is about 400 quads, or 400x10^15 Btu, that's (4x10^17 Btu)/(1.35x10^4 Btu/kg) = 3.08x10^13 kg of O2 consumption per year. That gives us a time T of about T = (3.59x10^17 kg)/(3.08x10^13 kg/yr) = 1.166x10^4 yrs, or about 11,660 years to get there. I would expect at least humans to adapt in that time, but who knows? I hope I got all that right. Regards, Horace Heffner
